Telerobotics, in which a robot is controlled from a distance, is an area of robotics that is useful in many applications, such as in surgery. Telerobotic systems consist of a master robot and a slave robot. In surgery, the surgeon directly controls the master robot, which results in motion of the slave robot at the patient. The master robot and slave robot, which are physically separated, may be close to each other (e.g., in the same room) or remote from each other (e.g., on different continents).
In replicating the environment found in a conventional procedure, the user interface of the master robot ideally accommodates the desired motions of the surgeon (i.e., includes sufficient degrees of freedom), and mechanically simulates the feel and touch of the actual environment (i.e., provides haptic feedback). To provide haptic cues, actuators in the slave robot typically generate an opposing force against a user-manipulated item such as a grasper or stylus. These forces are transmitted from the actuators to the stylus through a haptic device transmission. Haptic device transmissions ideally have minimal friction, minimal inertia, minimal or no cogging and grinding, high stiffness, and no backlash. Haptic devices have historically included cable and pulley transmissions, which most effectively address theses requirements.
However, simply providing haptic feedback is not enough during certain procedures, such as those requiring high bandwidth haptics, in which the tactile feedback to the user is updated at a high frequency. For example, haptics with low inertia and high bandwidth are advantageous in microsurgery, which typically involves procedures performed by hand under a microscope. This is due in part to the low mass and low inertia of microsurgical tools, and in part to the subtle, high frequency haptic cues used for navigation. As one illustrative example, a stapedotomy (during which the surgeon drills a hole in the stapes footplate in the ear for the insertion of a prosthesis) is ideally performed with a haptic device having high bandwidth and low inertia. In this procedure, care must be taken to avoid perforating the cochlear membrane behind the stapes, making a stapedotomy analogous to drilling through an eggshell without puncturing the membrane inside the egg. The haptic cue that a surgeon monitors to avoid damaging the cochlear membrane is the sudden drop in mechanical resistance on the drill during penetration of the bone. Low bandwidth haptic devices are, by definition, slower to respond and would potentially mask this cue and possibly increase the incidence of complications if used as telerobotic masters.
Thus, there is a need in the haptics field to create an improved haptic device for surgery with lower effective inertia and higher bandwidth, which may also be adapted to use in a wider range of types of robotic surgery and simulation. This invention provides such an improved haptic device for surgery.